The present disclosure relates to an organic EL element, an organic EL display panel, and a method of manufacturing an organic EL display panel.
In general, an organic EL (Electro-Luminescence) display panel has a configuration in which a light emitting layer is disposed between an anode and a cathode. In such an organic EL display panel, at least one of the anode and the cathode is a light-transmitting electrode through which visible light is transmitted, for taking out the light from the light emitting layer.
For example, in a so-called top emission type organic EL display panel, an electrode on the substrate side is a light-reflective electrode which reflects visible light, whereas an electrode on the opposite side is a light-transmitting electrode, and, by this configuration, light take-out efficiency is enhanced.
The light-reflective electrode is formed by use of, for example, silver (Ag) or aluminum (Al), whereas the light-transmitting electrode is formed by use of, for example, a metallic oxide such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide) (see, for example, Japanese Patent Laid-open No. 2014-140048).
In the electrode formed by use of a light-transmitting material (hereinafter referred to as “light-transmitting electrode”), it is demanded to realize both a low resistance and a high transmittance. For this reason, in addition to the above-mentioned metallic oxide, use of a metal thin film has been investigated. In the light-transmitting electrode, uniformity of film properties is demanded, for further efficient transmission of light and for stabilization of characteristics such as resistivity. Therefore, the light-transmitting electrode is formed by vapor deposition, a sputtering method or the like.